Abstract: In order to optimize the conservation tillage measures and improve the soil fertility, the study of soil organic carbon and nitrogen distribution characteristics and content changes of different growth stages in broad bean growth period under long term conservation tillage in southwest China was implemented. There were six treatments including traditional tillage, ridge tillage, traditional tillage with half amount of straw mulching, ridge tillage with half amount of straw mulching, traditional tillage with full amount of straw mulching, ridge tillage with full amount of straw mulching. The results show that soil total organic carbon(TOC), total nitrogen(TN), active organic carbon(AOC), particulate organic carbon(POC), the content of water soluble nitrogen(DN) distribution decreased in the order:0-10 cm layer > 10-20 cm layer under the different treatments. And the overall fluctuations are not large over time. During the period of broad bean growth, under the conditions of no straw mulching, soil TOC, TN, AOC and POC of ridge tillage are more than traditional tillage. However, with straw mulching, ridge tillage reduced soil TOC and POC, and with the increase of straw mulch, the contents of soil AOC and POC decreased. At the same time, whether flat or ridge, straw mulching was better than no straw mulching in terms of improving soil TOC, TN, AOC and POC. Correlation analysis showed that TOC was significantly related to TN, DN, AOC; TN was significantly related to POC, DN, AOC; POC was only correlated significantly with DOC; DOC was significantly positively correlated to DN; DN was very significantly positively correlated to AOC. The results showed that single ridge tillage or straw mulching could more effectively improve the status of soil carbon and nitrogen; and there was a certain coupling relationship between the different components of soil organic carbon and nitrogen.